dicentric fragments. Applications Dicentric chromosomes are studied in model organisms such as yeast (Saccharomyces cerevisiae). The use of S. cerevisiae as a classical genetic system dates back to the 1950s due to its feasibility in transformation by recombinant DNA. Broken chromosomes that lead to acentric and dicentric fragments can be studied in S. cerevisiae due to its known ability to tolerate aneuploidy, an abnormal number of chromosomes. Strains of S. cerevisiae that tolerate aneuploidy can stabilize products of broken chromosomes during proliferation, which can be recovered and studied in a laboratory setting. Cytogenetics Centromere function has been the focus of many laboratory analyses, involving techniques like fluorescence in situ hybridization (FISH) and chromosomal banding (C-banding). FISH involves the use of fluorescent probes to detect and localize specific DNA sequences on chromosomes, and centromere-specific probes can be used to measure dicentric chromosome frequencies. This technique allows for the testing of human blood samples and tissue samples, which have been historically adopted by radiation laboratories. C-banding is a staining technique that can be used to visualize dicentric chromosomes. It specifically stains constitutive heterochromatin, which are regions of the chromosome at or near the centromere. Consequences The existence of dicentric chromosomes has clinically relevant consequences for individuals, which may live with intellectual, neurological and physical disabilities. Tailed nuclei are signatures of radiation exposure in human tissue, microbiota, and aquatic invertebrates from the wake of recent nuclear disasters. Additionally, they are used as potential biomarkers to screen for certain genetic syndromes present in human populations. Pseudodicentric chromosomes Dicentric chromosomes may lead to pseudodicentric mutations, in which one of the centromeres on the chromosome becomes inactivated. This can have severe clinical consequences for patients, as observed in severe progressive neurological and intellectual disorders such as Kabuki syndrome, a pediatric congenital disorder. Kabuki syndrome is one of the most widely studied syndromes that involve the pseudodicentric chromosome. Other characterized syndromes have also been linked to pseudodicentric chromosomes, such as Edwards syndrome, a trisomy of chromosome 18, and Turner syndrome, a loss (or partial loss) of the X chromosome. Pseudodicentric chromosomes alone do not define these syndromes, because the contribution of other chromosomal abnormalities are also considered, such as the presence of isochromosomes in Turner patients. See also Chromosomal inversion Telomeres Cytogenetics Nuclear radiation Intellectual disorders References Chromosomes